1. Field of the Invention
This invention relates to adjustable output pumps for liquids.
2. Background of the Prior Art
It has heretofore been proposed to provide adjustable output pumps of the expandible chamber type employing bellows, diaphragms or pistons.
It has also heretofore been proposed to provide bellows pumps such as are shown in the U.S. Patents to Geisler, No. 1,454,886, and Fowler, No. 2,553,247 which have eccentric drives.
In the U.S. Patents to Bennett, No. 2,975,599 and Fazakes, No. 4,031,778 adjustable eccentrics are shown in which the adjustment of eccentricity is by a diametrical shift, while in the U.S. Patent to Mattox, No. 2,254,539 an adjustable lever or rocker arm with a limiting set screw is provided actuated by a cam to vary the stroke of the lever.
Most of the bellows heretofore employed in pumps were of metal which is not suitable for use with liquids containing chemicals or which otherwise can cause corrosion. The U.S. Patents to Smith, No. 3,529,908 and Mondaidis, No. 3,376,868 show pump bellows of resilient elastomeric material having a high elastic recovery such as polypropylene. The U.S. Patent to Laerdal, No. 3,363,833 shows a pump bellows of rubber, natural or synthetic.
In some of the bellows pumps heretofore available the resiliency of the bellows was relied upon on the suction stroke for restoring the bellows to its precompressed condition.
In most of the pumps including bellows pumps, diaphragm pumps and piston pumps for pumping small quantities of liquids heretofore proposed by others, the structures are complex and expensive to construct, usually require assembly and replacement of components to be made by the manufacturer or in the shop, are not suited for easy adjustment of the stroke and are subject to corrosion by the liquid to be pumped.